Encasement for the tail section of a rocket with a central nozzle and extendible control vanes

ABSTRACT

A rocket has a generally cylindrical casing and a central nozzle extending from the rear end portion of the casing and smaller cross-section than the rear end portion. Within the space around the nozzle there are provided vanes mounted for swinging movement between a retracted position within the space and an operating position in which they extend out of the space. A substantially cylindrical cover encloses the greater part of this space. The vanes can be projected through slots in this cover by turning the cover.

nite States atet I 1 Bode [451 Dec. 10, 1974 [54] ENCASEMENT FOR THE TAIL SECTION OF 3,136,25 0 6/1964 Humphrey 1. 244/327 A ROCKET A CENTRAL NOZZLE FOREIGN PATENTS OR APPLICATIONS AND EXTENDIBLE CONTROL VANES 745,252 2/1956 Great Britain 244/329 [76] Inventor: Helmut Bode, Falladastrasse la, 831,221 3/1960 Great Britain 244/327 Celle, Germany 903,842 8/1962 Great Britain 244/329 Filed: S pt. 969 1,144,624 2/1963 Germany 244/329 PP 863,412 Primary Examiner-Verlin R. Pendegrass Related US. Application Data [5 7 ABSTRACT A rocket has a generally cylindrical casing and a central nozzle extending from the rear end portion of the casing and smaller cross-section than the rear end portion. Within the space around the nozzle there are provided vanes mounted for swinging movement between a retracted position within the space and an operating position in which they extend out of the space. A substantially cylindrical cover encloses the greater part of this space. The vanes can be projected through slots in this cover by turning the cover.

, 22 Claims, 25 Drawing Figures PATENTEB DEC 1 0 I974 SHEET 2 OF .6

w 5 M p 0 5 M r U PATENTEQ an: 1 019m Sum 3 BF 6 PATENTEB 0521 01974 SHEET 6 0F 6 ENCASEMENT FOR THE TAIL SECTION OF A ROCKET WITH A CENTRAL NOZZLE AND EXTENDIBLE CONTROL VANES This application is a continuation-in-part of Ser. No. 654,022, filed July 17, 1967, and now abandoned.

The invention relates to rockets with extendible, especially pivoted, control vanes and to an encasing or enclosing means for such vanes.

In order to make it possible to discharge or fire rockets with stabilizing control vanes from tubes, the control mechanism is so constructed that the guide blades or vanes, up to the time of discharge of the rocket, are kept within the space between the nozzle and the imaginary prolongation of the rocket housing, and are first projected into their flight positions after the release from the launching tube. Such control arrangements have many uses, but especially control arrangements with vanes pivoted about axes at least approximately parallel to the central axis of the rocket. As with all other known control arrangements with movable blades or vanes, these pivoted blade constructions have the disadvantage that the mounting structure for permitting movement of the blades, such as the bearing brackets, produce a considerable disturbance of the air stream, which, especially in connection with the most unsatisfactory flow conditions at the transition from the combustion chamber'to the nozzle which are found in rockets, can result in violent disturbances in flight.

The primary object of the present invention is to overcome this disadvantage.

For a rocket with a central nozzle and pivoted control vanes, the invention provides a tail structure cover or enclosure, which is of such a nature that, when the rocket leaves the launching tube, the automatic projection of the control vanes is not interfered with; namely, a one-piece or multiple-piece thin-walled shell which during the flight of the rocket forms an outer covering of the spaces between the blades which extends at least to the rear end of the blades, and preferably to the rear end of the casing or nozzle, and forms substantially a prolongation of the tubular casing of the rocket. In a more detailed sense, the invention provides a one-piece shell or encasement. formed of materials conventional in rockets such as steel, light metal, plastics or the like, coaxial with the rocket axis and provided with a number of slots corresponding to the number of blades, through which the blades can move without hindrance during the retraction and extension of the blades. Of course, instead of a shell formed of one piece of material, a shell formed of a plurality of connected parts can be used.

The shell or cover can be so constructed and arranged that it is mounted on the tail section to turn about its axis between two limit positions corresponding to the limit positions of the vanes, the turning movement required for the projection of the vanes being produced by springs urging the vanes to projected position or by one or more separate springs arranged between the nozzle and the shell, which may supplement the action of the springs acting on the blades. It is also possible that, with a suitable arrangement of springs between the nozzle and the shell, the springs acting on the blades could be omitted.

Another arrangement which can be used separately or in conjunction with those previously described is one in which the shell at its rear end is provided with a numher of circumferentially spaced blades extending across the nozzle opening and sloping with respect to the direction of fluid flow through the nozzle. The first part of the moment produced by the gas stream of the propelling charge turns the shell to the end position in which the vanes are projected and thereafter imparts to the rocket a rotation which stabilizes its flight.

Because the blades at the beginning of their projective movement through the slots are almost flat with relation to the shell wall, the slots must be somewhat wider than the portions of the vanes which lie in the slots when the vanes are extended. In order to provide as complete as possible a closure of the spaces between the vanes, it is desirable to arrange for the vanes to form almost complete closures for the slots. For this purpose, the turning axes of the vanes are so positioned with respect to the diameter of the shell and the bearing bushings of the vanes are so constructed that the latter, when the vanes are projected, fit exactly in the slots and are flush with the outside of the shell.

Such measures for the closing of the slots can be avoided, however, if the enclosing shell, instead of being turnably mounted, is mounted for axial sliding movement on the rocket casing, and the slots are open at their rear ends. Such an arrangement can easily be constructed by having the shell held in front of the vanes when they are retracted and pushing it backwardswhen the vanes are projected. The width of the slots can then be exactly equal to the thickness of the blade area which they engage.

The invention further contemplates a construction in which a one-piece shell is fixed on the rocket tail section. In this case, in addition to a pivotal mounting of the vanes, the whole control arrangement is mounted for turning movement around the rocket axis, which may be achieved by pivotally mounting the blades on a ring turnably mounted on the nozzle, and providing, for turning the ring, one or more springs coiled in one or more convolutions around the nozzle, one end of each spring being connected to the ring andthe other to the nozzle. Instead of or in addition to such springs, a number of rotation producing blades extending across the nozzle opening can be provided at the rear end of the ring, and the vane projecting springs can I somtimes be eliminated. In order to save space, it is desirable to provide the ring with lateral recesses or slots and to mount the bearing bushings of the vanes in these slots.

In a further form of the invention, the enclosure can be formed by cylindrically curved segments connected to the nozzle and equal in number to the vanes. This is preferably so designed that these segments, when the vanes are retracted, lie between the vanes and the nozzle whereas, then the vanes are fully projected, the segments form a cylindrical cover around the nozzle closing the spaces between the vanes.

Further objects and advantages of the invention will appear more fully from the following description, especially when taken in conjunction with the accompanying drawings which form a part thereof.

In the drawings:

FIGS. la and lb show in side elevation a rocket with a tail section not provided with an encasement, with the vanes in retracted and projected positions respectively;

FIGS. 2a and 2b are similar views of a rocket with a tail section cover;

FIGS. 3a to 3d show in cross-section (3a and 3c) and in elevation (31) and 3d) respectively a rocket tail section with retracted (3a and 3b) and projected (3c and 3d) vanes;

FIGS. 4a and 412 show a modification of FIGS. 3c and 3d;

FIGS. 5a and 5b show, on a larger scale, a modification of FIGS. 3a and 3c;

FIG. 6 shows a further modification;

FIGS. 7a and 712 show another modification;

FIGS. 8a and 8b show a form with an axially movable shell;

FIGS. 9a9d show a modification with a shell fixed on the rocket casing;

FIGS. 10a and 10b show another form of FIGS. 9a and 9b; and

FIGS. 11a and 11b show a construction using resilrent segments.

In FIG. la, the vanes 4 of the control arrangement 3 mounted on the central nozzle 2 of the rocket l are held in retracted position by a holding ring 5 which, upon the discharge of the rocket from the launching tube (not shown) is pulled off and releases the vanes 4, so that these vanes. upon the exit of the rocket from the tube, under the influence of vane projecting springs arranged on the turning axes 6 of the vanes (these springs not being shown) can move into the exactly radical positions shown in FIG. lb. Of course, the vanes can be suitably secured in their projected positions.

As is obvious from a comparison with the rocket 1 of FIGS. 2a and 2b with an enclosed tail section, the latter is given very good aerodynamic properties, both because the abrupt transition between the combustion chamber or rocket casing and the nozzle as well as the pivotal mounting parts for the vanes which might prevent a smooth flow of air are completely covered over and only the flight stabilizing parts of the projected vanes 4 (FIG. 2b) extend beyond the shell 7 which forms an accurate prolongation of the rocket casing.

According to FIGS. 30 to 3d, the covering member is a cylindrical shell 7 coaxial with and turnable about the axis 9 of the tail section, of equal diameter with the rocket casing and provided with slots 8. Guide or control vanes 4 are turnably mounted by bearing bushings 12 on the axles 6 carried by the nozzle 2. They are held in retracted position (FIGS. 3a and 3b) with their ends against the edges of the slots 8 against projection under the influence of vane projecting springs 13 by a launching tube (not shown) or by a holding ring as shown in FIG. la.

This limits the turnability of shell 7, with which they terminate flush on the outside, in one direction, here counterclockwise. Between the shell 7 and the nozzle 2 a spring 14 is arranged with its ends fastened to the two parts.

As long as the rocket is in the launching tube, the

vanes 4 are prevented from moving out through the slots 8 to projected position. Likewise the shell 7 is held with the vanes 4 in the position shown in FIGS. 3a and 3c, spring 14 being under tension. After the rocket leaves the tube, or during the flight, the projection of the vanes 4 through the slots 8 is no longer prevented, so that simultaneously with the clockwise turning of shell 7 by expansion of spring 14, the vanes 4 are projected by springs 13 to the position shown in FIGS. 3c and 3d. The engagement of the vanes 4 with the leading edges 11 of the slots of course takes place only when the spring 14 is fully expanded or has such small tension that it cannot turn shell 7 any further. It is advantageous, however, to provide a stop to limit turning movement of the shell 7, because the shell can then turn faster in the latter part of its movement and will always take the same final position. The fact that the shell 7 can turn somewhat further, even up to the point where its trailing slot edge 15 engages the vane 4, results in no disadvantage, because the vanes 4 in their projected position may, of course, be held, not by the slots 7, but rather by stops (not shown) carried by the vanes and vane axles or the like. As is clear from FIGS. 3b and 3d, the slots 8 have a somewhat greater axial length than the vanes 4. In the retracted position of FIG. 3b the forward edges of the vanes lie close to the forward ends of the slots, whereas in the extended position of FIG. 3d the rear ends of the vanes are near the rear ends of the slots, or are somewhat displaced axially from the retracted position. It should be understood that the vanes 4 can be fixed in position by this axial rearward movement, without affecting the operation of the shell. Of course, such a fixing of the vanes 4 can be achieved in some other way or be omitted, in which case the slots can be of the same length as the vanes.

FIGS. 3b and 3d show an annular flange 16 screwed or otherwise removably secured at the end of nozzle 2, which serves to retain and center the shell 7 on the tail section. A further centering guide is preferably provided at the front end of the shell 7.

In the form of FIGS. 4a and 4b, a special spring 14 for the shell 7 is omitted, and instead at the rear end of the shell 7 is secured a bladed ring 17 with rotationproducing blades 18 extending at least partly across the open end of the nozzle and sloped with respect to the direction of flow of propelling gas. These blades may be formed on the shell or on a separate ring fastened to the shell.

The conditions are about the same as in the form of FIG. 3. As long as the rocket is inside the tube, the vanes 4 and shell 7 are held in their retracted or first end position. After the rocket leaves the .tube, the vanes 4 begin to move out under the effect of springs 13 to the projected position of FIG. 4a and at the same time the shell 7 is turned by the turning moment of the propelling gases on blades 18 acting through ring 17, until finally it engages with its trailing slot edges 15 the fully projected vanes 4, so that further turning with respect to the rocket is stopped and its other end position is reached. In the further travel of the rocket, the moment produced by the action of the gas stream on blades 18 through ring 17 and shell 7 produces a flightstabilizing rotation of the rocket.

As FIGS. 3c and 4a show, the vane outlet slots 8 are for the most part not covered by the projected vanes 4. FIGS. 5a and 5b show a means to close the slots, in which each bearing bushing 19 of the vanes is provided on the trailing side of the vane 4 with a shoulder-like thickening 20, which, when the vanes are projected, lies flush with the outside of the shell 7 and fits exactly in the slot 8 so as to close it completely. For this purpose the trailing edges of the slots and the thickenings 20 are shaped to conform with each other.

The slot closure of this type can also be used if the bearing bushing 19 does not extend over the whole length of the vane 4 but only at its front and rear ends. In this case, as is shown in broken lines, the thickening 20 is formed as a thin flange and is screwed or otherwise fastened to the bushings 19.

As FIGS. 6 shows, a complete closure of the slots 8 can also be achieved if a thickening 20 of the bushing 19 is provided in conjunction with a vane 4 which is radical to the 'axis of turning of the bushing, which is shown only in one of many possible forms in the drawmg.

In a similar way as in FIGS. 5 and 6, in FIGS. 7a and. 7b there is provided for closing the slots an enlargement 20 and the vane bushing 19; however, here the trailing edges of the slots are provided with resilient edge strips 15 riveted on the shell 7, which, when the vanes 4 are retracted, bend inwardly towards the nozzle, as shown in broken lines in FIG. 7a, and which, when the vanes are projected, engage the enlargement and are pressed into a position flush with the outer surface of shell 7, so that, when the vanes are fully projected. they fit snugly into recesses 23 in the enlargements 24. It would also be possible for the edge strips to have the position shown in solid lines in FIG. 7a, and to be shifted inwardly by engagement with the vanes 4, which under the conditions shown takes place if the vanes 4 are substantially horizontal. This modification is important if the slots 8 are made relatively narrow,

and it is especially useful if the retracted vanes 4 engage with their outer ends not on the edges 11 but on the free ends of the edge strips 22, in which case it must of course be made certain that the edge strips cannot push over the outer ends of the vanes. But this form of cover for the slots is of course not limited to the use of the vane shape shown and can be used additionally to or only on the leading slot edges 11.

In FIGS. 80 and 8b, the cover 7 is formed as a shell axially slidable on the outside of the rocket casing, the slots 8 being open at their rear ends. FIG. 8a shows the position of the parts within the launching tube before the rocket is fired. The vanes 4 are held in retracted position by the holding ring 5. The shell 7 is held in its forward end position on the rocket casing by engagement of its rear edge against the forwardly directed edges 25 of the vanes 4, or of the bearing bushings 19, the parts being so constructed that, when the vanes are fully projected, the shell 7 is released, that is, engagement of its rear edge 24 no longer exists. But the holding and release of the shell 7 when the vanes are retracted and projected could be accomplished in other ways.

When the rocket l is launched, the holding ring 7 remains in the launching tube (not shown), so that the vanes 4, after the rocket leaves the tube, under the action of diagrammatically indicated vane projecting springs 13 are turned on their axes 6 and moved to the positions shown in FIG. 8b. The holding of the shell 7 is thus rendered ineffective, so that the shell can slide back to its rearward end position (FIG. 8b), the vanes 4 sliding into the slots 8. In such a construction in which the shell 7 is first released only when the vanes reach their fully open position, the width of the slots can be exactly equal to the thickness of the corresponding parts of the vanes 4, so that a very good streamlined enclosure of the rocket tail structure is obtained.

The rearward movement of the shell 7 to its rearward end position on the rocket casing can with such a releasing arrangement in certain cases by produced only by the drag exerted on the shell when the rocket is in flight. It is however desirable to arrange springs inside the shell 7 which are tensioned when the shell is in its forward position and which push the shell backward when it is released.

In the form of FIGS. 9a to 9d, the enclosing shell 7 is constructed as an exact prolongation of the rocket casing fixed on the nozzle 2, while the projection of the vanes 4 through the slots 8 corresponds to that shown in FIGS. 3 and 4. The vanes 4 are turnably mounted about axes .6 on a ring 26, which in turn is journalled on the nozzle 2. For projecting the vanes, projecting springs 13 are mounted on the axes 6, while for turning the ring 26 a spiral spring is arranged between the ring and the nozzle 2, which is connected at one end to the ring and .at the other end to the nozzle. To save space, the ring. 26 is provided in the area of the vane bearings with elongated slots 30. In this form also the vanes 4 are secured in projected position by movement axially of the rocket, for which purpose the slots 8 of the shell 7 are made somewhat longer than the vanes.

FIGS. 9a and 9b show the position when the rocket is in the launching tube. As soon as the rocket leaves the tube, spiral spring 27 and vane projecting springs 13 simultaneously turn the ring 26 with the vanes carried thereby and project the vanes, so that they take the position shown in FIGS. 9c and 9d. The use of the measures shown in FIGS. 3 and 7 can give a complete closure of the slots 8, while the use of the teaching of FIG. 6 is also applicable.

In the modification of FIGS. 10a and 10b, the spiral spring 27 is omitted and instead the ring 26 is journalled at the rear end of the nozzle and is provided with a bladed ring 17, 18, like that of FIG. 4, for turning the ring 26 and the rocket itself during its further flight.

According to FIGS. 11a and 11b, the cover is formed of a number of generally cylindrically bent resilient segments 31, equal in number to the number of vanes, which are fastened tothe rocket structure at each end by being secured to brackets 33-.

When the vanes are retracted, the cylindrically curved parts of the segments 31 extend between the vanes and the nozzle 2 and are held in such position by the vanes. When the vanes are projected, the containment of the segments 31 ceases, so that these because of their resilient nature can bend outward until they engage with their free edges under the stop shoulders 34 on the vane bushings l9 and, in prolongation of the rocket casing, almost completely close the spaces be tween the vanes 4.

Either in the form of FIGS. 11a and 11b, or if the closing member is formed as a turnable shell 7, it is not essential that the cover should form a cylindrical surface. It could also be a slightly conical or ogival rearwardly tapering shape. Likewise the vanes need not be flat, but can be curved or slightly spiral and may deviate from the axial plane of the rocket.

It will be clear that there is thus provided, in a rocket with a central nozzle, a vane mounting means and a cover forming means, one of which is movable with respect to the rocket.

While I have described herein some embodiments of my invention, I wish it to be understood that I do not intend to limit myself thereby except within the scope of the claims hereto or hereinafter appended.

I claim:

1. In a rocket having a generally cylindrical casing and a central nozzle extending from the rear end portion of said casing and of smaller cross-section than such rear end portion, vane means including at least one rigid control vane, means on said rocket on the outside of the nozzle and within a space concentric with and of the same diameter as the rear end portion of the casing pivoting said vane for swinging movement between an inoperative retracted position substantially entirely within said space and an operative position in which the vane extends outside the space, and means carried by said rocket to form a substantially cylindrical cover enclosing at least the greater part of the periphery of said space, one of said vane mounting means and said cover forming means being movable with respect to the rocket during movement of the vane to operative position.

' 2. In a rocket as claimed in claim 1, said cover forming means comprising a series of resilient bent segments within said space each secured to the rocket adjacent each vane pivot and extending circumferentially to a point close to an adjacent blade pivot, said segments lying inside the vanes in their retracted positions and springing out substantially flush with the prolongation of the casing when the vanes move to their extended positions.

3. In a rocket as claimed in claim 2, said vanes having stop means carried thereby engageable by the free edges of the segments when the vanes are in their projected positions to limit outward movement of the segments.

4. In a rocket having a generally cylindrical casing and a central nozzle extending from the rear end portion of said casing and of smaller cross-section than such rear end portion. a plurality of rigid control vanes,

means on said rocket on the outside of the nozzle and within a space concentric with and of the same diameter as the rear end portion of the casing pivoting said vanes for swinging movement between inoperative retracted position substantially entirely within said space and operative positions in which the vanes extend outside the space, and means carried by said rocket to form a substantially cylindrical cover closing at least the greater part of the peripheral portions of such space between the extended vanes, one of said vane mounting means and said cover forming means being movable with respect to the rocket during movement of the vanes to operative position.

5. In a rocket as claimed in claim 4, said cover forming means being movable with respect to the rocket.

6. In a rocket as claimed in claim 4, one of said cover forming means and said mounting means being turnable about the axis of the nozzle.

7. In a rocket as claimed in claim 4, said cover forming means being slidable in the direction of the nozzle axis.

8. In a rocket as claimed in claim 4, said cover forming means comprising a plurality of parts movable with respect to the rocket.

9. In a rocket as claimed in claim 4, said cover forming means being fixed to the rocket and said vane mounting means being turnable about the nozzle axis.

10. In a rocket having a generally cylindrical casing and a central nozzle extending from the rear end portion of said casing and of smaller cross-section than such rear end portion, a plurality of rigid control vanes,

means on said rocket on the outside of the nozzle and within a space concentric with and of the same diameter as the rear end portion of the casing pivoting said vanes for swinging movement between inoperative retracted position substantially entirely within said space and operative positions in which the vanes extend outside the space, and means carried by said rocket to form a substantially cylindrical cover closing at least the greater part of the peripheral portions of such space between the extended vanes while permitting movement of the vanes from the retracted to the projected positions.

11. In a rocket as claimed in claim 10, said rocket being elongated, said cover forming means comprising a cylindrical shell coaxial with the rocket longitudinal axis having slots therein for passage of the vanes therethrough.

12. In a rocket as claimed in claim 11, said shell being turnable about the rocket longitudinal axis.

13. In a rocket as claimed in claim 12, said vanes and shell having cooperating means thereon operative in the retracted and projected positions of the vanes to limit the turning movement of the shell between first and second end positions.

14. In a rocket as claimed in claim 12, spring means connected between the rocket and the shell for turning the shell towards said second end position.

15. In a rocket as claimed in claim 14, said spring means being at least substantially completely untensioned in said second end position.

16. In a rocket as claimed in claim 12, in which said slots are wider than the thickness of the vanes, said vanes having enlargements thereon fitting into said slots when the vanes are in projected position.

17. In a rocket as claimed in claim 16, said shell having resilient inwardly bent edge strips at'the trailing edges of the slots engageable by said enlargements to be moved thereby, when the vanes move to projected position, to positions flush with the shell.

18. In a rocket as claimed in claim 17, said enlargements having recesses therein in which the free ends of the edge strips engage in such flush position.

19. In a rocket as claimed in claim 12, means for turning said shell comprising rotation-imparting blades secured thereto in the path of gases issuing from said nozzle.

20. In a rocket as claimed in claim 12, means mounting said shell on the outside of the rocket for movement in the direction of the axis thereof between a first forward position in front of said vanes and a second rearward position opposite said vanes, said slots being open at their rear ends for sliding engagement with the projected blades in said rearward position.

21. In a rocket as claimed in claim 20, said shell and said vanes and vane mounting means having cooperating means thereon engageable when the vanes are in the retracted position to prevent rearward movement of the shell.

22. In a rocket as claimed in claim 1 1, said shell being fixed on the rocket, said vane mounting means comprising a ring turnably mounted in said space, said vanes being pivotally mounted on said ring. 

1. In a rocket having a generally cylindrical casing and a central nozzle extending from the rear end portion of said casing and of smaller cross-section than such rear end portion, vane means including at least one rigid control vane, means on said rocket on the outside of the nozzle and within a space concentric with and of the same diameter as the rear end portion of the casing pivoting said vane for swinging movement between an inoperative retracted position substantially entirely within said space and an operative position in which the vane extends outside the space, and means carried by said rocket to form a substantially cylindrical cover enclosing at least the greater part of the periphery of said space, one of said vane mounting means and said cover forming means being movable with respect to the rocket during movement of the vane to operative position.
 2. In a rocket as claimed in claim 1, said cover forming means comprising a series of resilient bent segments within said space each secured to the rocket adjacent each vane pivot and extending circumferentially to a point close to an adjacent blade pivot, said segments lying inside the vanes in their retracted positions and springing out substantially flush with the prolongation of the casing when the vanes move to their extended positions.
 3. In a rocket as claimed in claim 2, said vanes having stop means carried thereby engageable by the free edges of the segments when the vanes are in their projected positions to limit outward movement of the segments.
 4. In a rocket having a generally cylindrical casing and a central nozzle extending from the rear end portion of said casing and of smaller cross-section than such rear end portion, a plurality of rigid control vanes, means on said rocket on the outside of the nozzle and within a space concentric with and of the same diameter as the rear end portion of the casing pivoting said vanes for swinging movement between inoperative retracted position substantially entirely within said space and operative positions in which the vanes extend outside the space, and means carried by said rocket to form a substantially cylindrical cover closing at least the greater part of the peripheral portions of such space between the extended vanes, one of said vane mounting means and said cover forming means being movable with respect to the rocket during movement of the vanes to operative position.
 5. In a rocket as claimed in claim 4, said cover forming means being movable with respect to the rocket.
 6. In a rocket as claimed in claim 4, one of said cover forming means and said mounting means being turnable about the axis of the nozzle.
 7. In a rocket as claimed in claim 4, said cover forming means being slidable in the direction of the nozzle axis.
 8. In a rocket as claimed in claim 4, said cover forming means comprising a plurality of parts movable with respect to the rocket.
 9. In a rocket as claimed in claim 4, said cover forming means being fixed to the rocket and said vane mounting means being turnable about the nozzle axis.
 10. In a rocket having a generally cylindrical casing and a central nozzle extending from the rear end portion of said casing and of smaller cross-section than such rear end portion, a plurality of rigid control vanes, means on said rocket on the outside of the nozzle and within a space concentric with and of the same diameter as the rear end portion of the casing pivoting said vanes for swinging movement between inoperative retracted position substantially entirely within said space and operative positions in which the vanes extend outside the space, and means carried by said rocket to form a substantially cylindrical cover closing at least the greater part of the peripheral portions of such space between the extended vanes while permitting movement of the vanes from the retracted to the projected positions.
 11. In a rocket as claimed in claim 10, said rocket being elongated, said cover forming means comprising a cylindrical shell coaxial with the rocket longitudinal axis having slots therein for passage of the vanes therethrough.
 12. In a rocket as claimed in claim 11, said shell being turnable about the rocket longitudinal axis.
 13. In a rocket as claimed in claim 12, said vanes and shell having cooperating means thereon operative in the retracted and projected positions of the vanes to limit the turning movement of the shell between first and second end positions.
 14. In a rocket as claimed in claim 12, spring means connected between the rocket and the shell for turning the shell towards said second end position.
 15. In a rocket as claimed in claim 14, said spring means being at least substantially completely untensioned in said second end position.
 16. In a rocket as claimed in claim 12, in which said slots are wider than the thickness of the vanes, said vanes having enlargements thereon fitting into said slots when the vanes are in projected position.
 17. In a rocket as claimed in claim 16, said shell having resilient inwardly bent edge strips at the trailing edges of the slots engageable by said enlargements to be moved thereby, when the vanes move to projected position, to positions flush with the shell.
 18. In a rocket as claimed in claim 17, said enlargements having recesses therein in which the free ends of the edge strips engage in such flush position.
 19. In a rocket as claimed in claim 12, means for turning said shell comprising rotation-imparting blades secured thereto in the path of gases issuing from said nozzle.
 20. In a rocket as claimed in claim 12, means mounting said shell on the outside of the rocket for movement in the direction of the axis thereof between a first forward position in front of said vanes and a second rearward position opposite said vanes, said slots being open at their rear ends for sliding engagement with the projected blades in said rearward position.
 21. In a roCket as claimed in claim 20, said shell and said vanes and vane mounting means having cooperating means thereon engageable when the vanes are in the retracted position to prevent rearward movement of the shell.
 22. In a rocket as claimed in claim 11, said shell being fixed on the rocket, said vane mounting means comprising a ring turnably mounted in said space, said vanes being pivotally mounted on said ring. 